Nope. We just have a bug here. JRuby 9k uses completely different internals than JRuby 1.7.x. JRuby 9k now converts a syntax tree into a set of virtual machine instrs and emits a line_num instr. In this case I am guessing the instrance variable + if ends up putting a line number instr in a place where we think we can cull it (or never emit it in the first place).

@enebo To add to this, there are other examples of this failed coverage, not just for 'if else' with instance variables. I saw a similar issue with .to_json() not getting covered. It's a more general problem I think, not limited to this example.

@mullermp yeah it would not surprise me very much. In fact it probably has nothing to do with the if/else specifically and more to do with us emitting line_num in combination of two elements (like if and an instance variable). I have fixed multiple coverage issues already so either this is a regression or oddly a case with no coverage in our tests.

Ok looked into this and wowsers it was not in IR at all. It was back in the AST. Basically anything which represents an ident during lexing ivar, cvar, gvar, keywords, constants would ask lexer for current position but lexer will advance past the ident in cases where the ident is last thing on a line and advance to next line (not 100% of the time but most of the time).

Fortunately, the lexer has a special position value for idents called tokline. I switched all obvious nodes made directly from idents to use tokline and it seems to have fixed this issue and probably many others.

I also ran simplecov specs and while there were 4 errors....none were related to positions changing. Thinking about whether we have any nice tests for this somewhere else too. Obviously this is not being captured in any test runs we normally do.

Awesome. I'll be trying this after release and I'll re-open if there's still any issues with coverage.

@mullermp yeah fantastic. We want perfect compat for coverage and will prioritize if we can.

looks like this fix doesn't cover all cases. here is an example of a constant being tested that gets 100% in MRI 2.4.2 and 0% in JRuby9000:

code:

MRI 2.4.2:

JRuby9000:

@zendes can you open this up as a new issue please?

I think this is part of the same issue. The original example I posted were just a simple one. I have issues such as coverage missing in multi-line hashes. And multi-line if statements conditions that are missed but can be resolved by editing the condition.

e.g.

foo << bar unless bool1 || #HIT
bool2 || #MISS
string1 != string2 #MISS

foo << bar unless bool1 || #HIT
!!(bool2 == true) || #HIT
!(string1 == string2) #HIT